This invention relates generally to overvoltage protection of power transmission systems, and more particularly to a sensor for monitoring a health of a surge arrester, such as a metal oxide arrester, installed in a power transmission system.
Overvoltages in power transmission systems occur as a result of lightning incidents, switching actions, and any other action that may cause overvoltages in the power transmission system. These overvoltages can cause damage to power transmission system assets. One of the ways that utilities protect against such overvoltages is by using surge arresters, such as a metal oxide arrester, which are installed in substations and power transmission conductors. These arresters are typically positioned in the vicinity of a power transmission asset and are used to limit the amount of voltage being passed to the power transmission asset by diverging surges to ground.
Metal oxide arresters have become the standard type of surge arrester. Metal oxide arresters consist of metal oxide varistor blocks connected in series which have a non-linear volt-current characteristic. These arresters can age due to (1) diverting multiple surges, (2) water intrusion in the housing, and (3) power frequency overvoltages. The aging of the arresters can result in their ultimate failure which often causes collateral damage to nearby power transmission assets and a safety hazard together with a potential outage.
Accordingly, there remains a need for a sensor that is capable of identifying high risk arresters prior to failure and capable of integrating with Supervisory Control and Data Acquisition (SCADA) systems to allow remote monitoring.